The background of the present invention is the field capsules which contain beverage or other comestibles (e.g. soup) ingredients. By means of an interaction of these ingredients with a liquid, a beverage or other comestible can be produced. The interaction can be for example an extraction, brewing or dissolution process. Such a capsule is particularly adapted to contain ground coffee in order to produce a coffee beverage by injecting hot water under pressure into the capsule and gaining a coffee beverage from the capsule.
Systems and methods for obtaining fluid comestibles from substances containing capsules are for example known from EP 512 470 A (Counterpart of U.S. Pat. No. 5,402,707).
The principle of this extraction process as far as it can be maintained in connection with the present invention can be summarized as follows.
An initially sealed capsule is inserted in a dedicated extraction chamber of the system in which water injection means are provided which enable a provision of water to the extraction chamber, e.g., by injection. In the extraction chamber, dedicated opening means are provided which generate at least one opening in a first wall of the capsule. Accordingly, water entering the capsule through the opening in the first wall is made to interact with ingredients contained in the capsule while traversing the interior of the capsule and is then made to leave the capsule through at least one opening/perforation created in a second wall of the capsule. As a result of the interaction, a beverage or other comestible will be produced which can be obtained directly from the capsule.
EP 870 457 A1 and WO 94/02059 show extraction methods and extraction machines for essentially symmetrical capsule.
It is important that the capsule is gas-tightly closed before use to ensure the freshness of the ingredients within a given shelf life.
Therefore, preferred capsules are closed by impermeable walls which are pierced only during use, such as by introduction of the capsule in the device.
However, the known capsules and the known beverage preparation devices suffer several drawbacks.
It is for example difficult that piercing of certain capsules is realized in a repeated manner. Especially, in combination with capsules made from plastics, the material can be relatively hard to pierce and the piercing members can become blunt relatively rapidly. As a result, new capsules can no longer be pierced with the same device and hence, a repairing or replacing of the piercing elements or the piercing member of the device becomes necessary.
Moreover, the piercing member of the device provides a single injection pattern in the capsule. It is thus not possible to vary the manner the liquid is injected into the capsule, such as the number of holes, the direction of injection, the depth of injection etc., unless a complicated injection commuting system as described in WO 2005/020768 is provided. However, such devices are complex and costly to produce.
Another problem is that when the capsule is removed from the device, the piercing member disengages from the capsule at the same time. As a result, large holes are typically left in the capsule, which provide a potential source of leakage for beverage residua such a coffee solids. A solutions exists which consists in adding an internal filter to prevent the exit of such residua such as in EP 1 165 398.
Another problem is that the piercing member comes in contact with the ingredients when puncturing or piercing the capsule. For certain ingredients, such as infant formula it is necessary to clean or sanitize the piercing member after each preparation cycle such as described in PCT/EP2008/057979.
WO 2006/030461 relates to a capsule which comprises a piercing element turned upwards in direction of an outer membrane. Piercing of the injection holes is obtained by the pressure of fluid which presses the membrane against the sharp elements. This solution, however, has several disadvantages. In particular, the membrane is easily able to be pierced by accident. Hence, if the user manipulates too much at the capsule, the membrane will be pierced before use, which causes rapid degradation of the ingredients. Moreover, the sharp edges being protruding into the direction of the user constitute a possible source of risk, since the user may sting himself. Moreover, resurgence of liquid or solids from the capsule is prevented in case the pressure within a receiving chamber and thus in the capsule is reduced after injection of liquid during operation of the device, as the membrane remains opened with the holes being uncovered.
The present invention therefore seeks to address the above-described problems. Moreover, the present invention aims at providing a solution to other problems as will appear in the rest of the description.